WSDL Example (Interface) WSDL Example (Implementation) Universal Description, Discovery and Integration. UDDI Usage

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1 Web Services Description Language WSDL Elements WSDL describes, how and where to access a service, i.e. the service interface, similar to remote object approaches like CORBA: What can the service do? - What operations are provided? - Abstract access port for message operations (input, output) What data types are used? - Definition of abstract messages (Data types, formats, ) How to invoke the service? - Transport protocol used (usually SOAP over HTTP) - Network address of a service A WSDL document consists of: Documentation Types Message Operation PortType Binding A human readable description (optional) Data type definitions used in operations Logical content of message; basing on the defined types, a definitions of the data being communicated An abstract definition of an action supported by the service Abstract set of operations, using messages as input/output Binding to concrete protocol and data format (SOAP, HTTP, ) Used for the description: XML Stubs for RPC are generated from a WSDL document 91 Service Port A single endpoint for communication (binding and network address) A collection of related endpoints 92 WSDL Elements WSDL Example (Interface) Port (e.g. Service Port Service Implementation: Equivalence in CORBA: IIOP and IOR <?xml version="1.0"?> <definitions name="stockquote" targetnamespace=" xmlns:tns=" xmlns:xsd1=" xmlns:soap=" xmlns=" Binding (e.g. SOAP) porttype operation(s) inmessage Binding outmessage Abstract interface Contact details about the service implementation Service Interface: Like in CORBA IDL: defining an interface Generation of stubs from this definition Different from IDL: an object reference is included in the specification <types> <schema targetnamespace=" xmlns=" <element name="tradepricerequest"> <complextype> <all> <element name="tickersymbol" type="string"/> </all> </complextype> </element> <element name="tradeprice"> <complextype> <all> <element name="price" type="float"/> </all> </complextype> </element> </schema> </types> 93 94

2 WSDL Example (Interface) WSDL Example (Implementation) <message name="getlasttradepriceinput"> <part name="body" element="xsd1:tradepricerequest"/> <message name="getlasttradepriceoutput"> <part name="body" element="xsd1:tradeprice"/> <porttype name="stockquoteporttype"> <operation name="getlasttradeprice"> <input message="tns:getlasttradepriceinput"/> <output message="tns:getlasttradepriceoutput"/> </porttype> <binding name="stockquotesoapbinding" type="tns:stockquoteporttype"> <soap:binding style="document" transport=" <operation name="getlasttradeprice"> <soap:operation soapaction=" <input> <soap:body use="literal"/> </input> <output> <soap:body use="literal"/> </output> </binding> <service name="stockquoteservice"> <port name="stockquoteport" binding="tns:stockquotesoapbinding"> <soap:address location=" </port> </definitions> Universal Description, Discovery and Integration UDDI Usage UDDI = Registry for advertise and discover Web Services Contains categorised information about businesses and the services they offer Association of services with a technical specification (defined in WSDL) 4. Return matching service info UDDI Registry 2. Submit description to UDDI registry Defines operations for registering services (Business, technical specifications, service and service endpoints) and for service discovery UDDI itself is realised as a Web Service Three types of UDDI registries: 1. Public directory, a collection of UDDI servers everyone can use without charge (see 5. Use WSDL to generate correct messages WSDL SOAP Processor (Requestor) 3. Query registry for WSDL of a service SOAP WSDL SOAP Processor (Provider) 1. Create WSDL describing service 2. Protected directories, shared by groups of companies with shared interests 6. Interact with service 3. Private directories, for company-internal usage or to share with cooperation partners 97 98

3 What is stored in the UDDI Registry? Relation to WSDL Specifications Different categories of information: 1. White pages 2. Yellow pages 3. Green Pages Business categories (Industry, product, geographic location) Description of how to do e-commerce with a provider Model for business process, technical service specifications, binding information Business name General business description Contact info (name, phone number, ) List of unique identifiers (e.g. domain name) businessentity ( who is it ) businessservice ( What is it ) bindingtemplate ( Where is it ) tmodel ( how to request it ) WSDL: Service Implementation <service> <port> <port> <types> <message> <porttype> <binding> Service Interface UDDI: BusinessEntity BusinessService BindingTemplate BindingTemplate tmodel UDDI Information UDDI Information Business Entity A business entity contains information about a business including its name, a short description, and some basic contact information. Each business can also be associated with unique business identifiers and with a list of categorizations that describe the business. UDDI provides built-in support for a number of taxonomies. Examples include SIC (Standard Industrial Classification codes), NAICS (North American Industry Classification System), UNSPSC (Universal Standard Products and Services Codes), and a geopolitical taxonomy. Businesses and industry groups can create additional taxonomies to categorize their businesses and services. Binding Templates Associated with each business service entry is a list of binding templates that provide information on where to find the service and how to use the service. A binding template may contain the access point of the service implementation and a pointer to information on how to use the service. The binding template also associates the business service with a service type

4 UDDI Information UDDI Example <businessdetail generic="2.0" operator=" truncated="false"> Service Types A service type, defined by a construct called a tmodel, defines an abstract service. Multiple businesses can offer the same type of service, all supporting the same service interface. tmodel A tmodel specifies information such as the tmodel name, a list of categories that describe the tmodel, and pointers to technical specifications for the tmodel. A tmodel may point to a WSDL document that describes the abstract service type. 103 <businessentity businesskey="413e39e d8-b dc0a53" operator=" <discoveryurls> <discoveryurl usetype="businessentity"> </discoveryurl> </discoveryurls> <name xml:lang="en">stock Company</name> <businessservices> <businessservice servicekey="b7e326a d8-b dc0a53" businesskey="413e39e d8-b dc0a53"> <name xml:lang="en">stockservice</name> <description xml:lang="en">stockservice_ibm testing</description> <bindingtemplates> <bindingtemplate bindingkey="b7f28ff d8-b dc0a53" servicekey="b7e326a d8-b dc0a53"> <description xml:lang="en"/> <accesspoint URLType="http"> </accesspoint> <tmodelinstancedetails> <tmodelinstanceinfo tmodelkey="uuid:b55ace d8-b dc0a53"/> </tmodelinstancedetails> </bindingtemplate> </bindingtemplates> <categorybag> <keyedreference tmodelkey="uuid:c0b9fe13-179f-413d-8a5b-5004db8e5bb2" keyname="portfolio Management" keyvalue="52392"/> </categorybag> </businessservice> </businessservices> </businessentity> </businessdetail> 104 UDDI Example Implementing Web Services <tmodeldetail generic="2.0" operator=" truncated="false"> <tmodel tmodelkey="uuid:b55ace d8-b dc0a53" operator=" <name> StockService Specification </name> <description xml:lang="en"> T-model for service interface definition </description> <overviewdoc> <overviewurl> </overviewurl> </overviewdoc> <categorybag> <keyedreference tmodelkey="uuid:c1acf26d d70-39b756e62ab4" keyname="uddi-org:types" keyvalue="wsdlspec"/> </categorybag> </tmodel> </tmodeldetail> Java has an API for XML-based remote procedure calls (JAX-RPC) which simplifies the process of building Web services that incorporate XML-based RPC It defines mappings between Java types and XML types that attempt to hide the details of XML and provide a familiar method-call paradigm JAX-RPC can be used to implement and call SOAP-based Web services described by WSDL using Apache's open source tools: Apache Tomcat for deployment Apache Axis for SOAP implementation

5 JAX-RPC Canonical Architecture Apache Axis Architecture How does it work? On the client side (Application 1) The Java support packages (e.g., org.apache.axis.client ) generate the appropriate SOAP request - according to the server that the client is accessing, send it to the Axis engine as an HTTP request, receive the resulting SOAP response, process it, and return the de-serialized return java object to the original calling client method. On the server side (Application 2) The Axis engine provides all of the support to process the SOAP request, call the indicated method in the deployed service class, receive its return java object, package it in a SOAP response, and return it via HTTP to the client. 109 First Step: Service Interface and Implementation package iis; import java.rmi.remote; import java.rmi.remoteexception; public interface HelloIF extends Remote { public String sayhello(string s) package iis; public class HelloImpl implements HelloIF { public String message ="Hello"; public String sayhello(string s) throws RemoteException { return message + s; Compile the classes: javac HelloIF.java HelloImpl.java throws RemoteException; Web Service Interface is derived from class Remote Methods required to throw RemoteException Note: no Web Service specific code here! 110

6 Configuration File Structure of WSDL All relevant information on Web Service <?xml version="1.0" encoding="utf-8"?> <configuration xmlns=" <service name="helloworldservice" targetnamespace=" typenamespace=" packagename="iis"> <interface name="cis.helloif"/> </configuration> Automatically derive WSDL from Interface and Configuration File wscompile -define -mapping build/mapping.xml -d build -nd build -classpath build config.xml <?xml version="1.0"> <definitions name="helloworldservice" Name Space Information > <types> <schema> definition of parameter data types in XML Schema (optional) </schema> </types> <message name="helloif_sayhello"> definition of a message (request, reply) <porttype name="helloif"> <operation name="sayhello"> definition of an operation (request reply pair) </porttype> <binding name="helloifbinding" type="helloif"> definition of a protocol binding (typically SOAP) </binding> <service name="helloworldservice"> <port name="stockquoteport"> definition of a port (an Internet address) </port> </definitions> abstract concrete WSDL Content Protocol Binding Provides message names and passing of parameters: <message name="helloif_sayhello"> <part name="string_1" type="xsd:string"/> <message name="helloif_sayhelloresponse"> <part name="result" type="xsd:string"/> Define message sequences corresponding to a service invocation <porttype name="helloif"> <operation name="sayhello" parameterorder="string_1"> <input message="tns:helloif_sayhello"/> <output message="tns:helloif_sayhelloresponse"/> </porttype> Implement abstract messages according to SOAP protocol <binding name="helloifbinding" type="tns:helloif"> <soap:binding transport=" style="rpc"/> <operation name="sayhello"> <soap:operation soapaction=""/> <input> <soap:body encodingstyle=" use="encoded"namespace=" <output> <soap:body encodingstyle=" use="encoded" namespace=" </output> </binding>

7 Service Access Location not known before deployment <service name="helloworldservice"> <port name="helloifport" binding="helloifbinding"> <soap:address location="replace_with_actual_url"/> </port> After deplyment: this can be published via UDDI <service name="helloworldservice"> <port name="helloifport" binding="tns:helloifbinding"> <soap:address location= " </port> 115 Deploy Service Deploying: tell the SOAP processor about your application Create a deployment descriptor Call the java command that deploys the web application <isd:service xmlns:isd=" id= URI of the application > Fill in your URI here </isd:service> <isd:provider type="java" scope="application" methods="sayhello"> <isd:java class= iis.helloimpl"/> </isd:provider> <isd:faultlistener> org.apache.soap.server.domfaultlistener </isd:faultlistener> Responsible for error handling Means that all SOAP requests will be sent to the same object List of available methods Name of Java class implementing the service in form packagename.classname Deploying: java org.apache.soap.server.servicemanagerclient deploy HelloDescriptor.xml 116 Register with UDDI Generate Stubs Client Configuration File <configuration xmlns=" <wsdl location="build/helloworld.wsdl" packagename="iis"/> </configuration> Automatically created using WSDL and client configuration file wscompile -gen:client -d build -classpath build config-client.xml

8 Client Application Creating Proxy (Stub) package iis; import javax.xml.rpc.stub; public class HelloClient { private String endpointaddress; public static void main(string[] args) { try { Stub stub = createproxy(); stub._setproperty (javax.xml.rpc.stub.endpoint_address_property, args[0]); HelloIF hello = (HelloIF)stub; System.out.println(hello.sayHello(args[1])); catch (Exception ex) { ex.printstacktrace(); private static Stub createproxy() { return (Stub) (new HelloWorldService_Impl().getHelloIFPort()); attaching _Impl to the service name is an implementation-specific naming convention Compiling, Packaging and Invoking Conclusion compile javac classpath system_jars:server_class_files: stub_class_files HelloClient.java package jar cvf hello-client.jar all_client_class_files:all_server_class_files Lots of problems in implementing distributed systems: synchronization, coordination, replication, transactions, heterogeneity, Useful concept: Middleware CORBA as supporting infrastructure for application as well as application programmers Lots of supporting services But: overloaded, new protocols, non-performant Web Services shall help Integrated with WWW Something new or just a new buzzword? Invoke the client: Lots of features known from CORBA are missing java classpath hello-client.jar:jwsdp-jars hello.helloclient There is no ideal middleware but searching for such a thing, old concepts are repeated frequently with new names